This invention relates to a device to selectively separate and remove larger sized objects from a mixture of larger and smaller sized objects. More specifically, the invention relates to the separation and removal of urine saturated litter clumps or soiled litter and solid animal waste, hereinafter referred to as animal waste, from surrounding clean litter.
Owners of domestic animals, such as cats, have long used a litter box for the toilet needs of their domestic animals. The litter box is filled with one of any number of particulate materials meant to absorb moisture and odor from the animal's wastes. These particulate materials are referred to as kitty litter or litter. Due to the unpleasant odor and the unsanitary nature of the wastes, the litter in the litter box must be cleaned on a regular basis for the benefit of both the animal and the owner of the animal.
A common type of litter box is a simple tray filled with litter. The usual method of cleaning the tray type litter box is to manually collect and dispose of the soiled litter and animal waste with perforated scoops or other devices developed to remove the soiled litter and animal waste from the clean litter. As this method of cleaning a litter box is unsanitary, unpleasant, time consuming and ineffective, the owner finds it necessary to repeat the cleaning process frequently and to replace the entire contents of the litter box periodically. To replace the contents of the litter box, the owner must pick up the tray type litter box and dump the contents; soiled litter and animal waste, and clean litter; into a plastic bag or other trash container. Since the soiled litter and animal waste often sticks to the bottom of the tray, spillage of the unsanitary and odoriferous contents may occur.
Cleaning a litter box is considered by most people to be such an unpleasant, time consuming and unsanitary task that they put it off until the odor from the litter box becomes unbearable and the entire contents of the litter box must be replaced. This causes a very unsanitary condition that could be a source of infection for the animal and the owner. This has led to the use of antiseptic and odor fighting chemical products that are dispersed throughout the litter. The open top and shallow sides of a tray type litter box do not allow proper dispersement of these antiseptic and odor fighting chemicals throughout the litter.
Because the above efforts to clean and deodorize the animal's litter box are either infrequently or ineffectively done by the owner, the owner finds that he or she is constantly replacing the litter in the litter box. This constant replacement of litter increases the cost of owning the animal. If the owner were to be able to easily and effectively clean the soiled litter and animal waste from the clean litter without the task being so unpleasant and time consuming, then the owner would find that the litter would not have to be replaced as frequently. This would reduce the cost of owning the animal.
When a domestic animal uses a litter box, it often digs, scratches, and otherwise kicks and distributes litter onto its wastes. Because of the shallow sides of the tray type litter box, the animal often kicks soiled litter and animal waste particles out of the litter box onto the area around the litter box. This creates an additional unsanitary and unpleasant condition for the owner to deal with.
In response to the above problems, inventors have developed a variety of automated, self-cleaning litter boxes. One type of automated, self-cleaning litter box consists of an open tray for litter that contains a rake-like device across the tray; an opening at the end of the litter tray to receive the soiled litter and animal waste separated by the rake; and a motor with controls to move the rake through the litter. One problem with this type of automated litter box is that it is much bigger than the simple tray type litter box and takes up more of the owner's living area. Another problem is that this type of automated litter box has a smaller area available for litter and for the animal to use the litter box than the simple tray type litter box, even though the automated litter box is physically larger. This type of litter box still allows the animal to kick soiled litter and animal waste out of the litter box. Since the top of the litter box is open, the odors from the soiled litter and animal waste still fill the owner's living space and, like the simple tray type litter box, antiseptic or deodorizer chemicals cannot be properly dispersed throughout the litter. A major disadvantage of this type of litter box is that the rake-like device must be widely spaced to reduce the loading on the electric motor and, therefore, is ineffective in cleaning soiled litter and animal waste from the clean litter. Also, since the electrical devices, used to automate the litter box, are near the litter area, there is the possibility that the animal could incur an electrical shock while using the litter box. There is also the danger that the automatic self-cleaning litter box will start a cleaning cycle while the animal is in the litter box, which could harm the animal. This type of litter box requires special bags or special boxes for its receptacle which are very expensive. Sometimes these special bags or special boxes are not readily available. For all of the above reasons, the tray type automated, self-cleaning litter box fails to meet the needs of the animal and the animal's owner.
Other types of automated, self-cleaning litter boxes are totally enclosed litter boxes with motorized mechanisms, located outside the enclosure, to either rotate the enclosure or to rotate separating devices inside the litter box enclosure. There are a number of problems with the totally enclosed types of litter boxes. They are large and require clearance on all sides of the litter box, which requires more of the owner's living space. It is difficult to remove soiled litter from these totally enclosed litter boxes because of the small opening in the enclosure for this purpose and due to the complex mechanisms inside these litter boxes. It is also difficult to add fresh litter to these litter boxes. If the litter box makes use of a plastic bag to collect animal wastes, then the owner must buy special, expensive plastic bags for the litter box. There is also the danger that the totally enclosed type of litter box will start a cleaning cycle while the animal is in the litter box, which could harm the animal. All of these components make the totally enclosed types of automatic self-cleaning litter boxes expensive to manufacture and expensive to maintain.
Because of the expense to purchase, the expense to maintain and the problems associated with the use of these automated, self-cleaning litter boxes, none of these automated, self-cleaning litter boxes have gained widespread acceptance.